Method and apparatus for making rod-shaped fillers for cigarette filters or the like

ABSTRACT

A tow which consists of filamentary filter material and is being converted into a continuous rod-like filler prior to wrapping to form a wrapped filter rod is being withdrawn from a bale wherein the filaments of the tow are likely to become interlaced or entangled with attendant short-lasting changes in tensional stresses upon the tow. Such short-lasting changes in the tensional stresses are damped upstream of the point where the tow is engaged by a pair of advancing rollers to insure that the tension in those increments of the tow which advance beyond such rollers is substantially constant. The damping action can be brought about by a roll which rests in a loop of the tow between the advancing rollers and the bale and which is biased by a spring which compensates for the weight of the roll. The latter rises in response to increasing tension in the loop to reduce the length of such loop and descends in response to decreasing tension of the loop to thereby lengthen the loop at a speed which is preferably proportional to the extent of changes in the length of the loop.

Greve 11 3,744,108 [451 July 10, 1973 [54] METHOD AND APPARATUS FOR MAKING ROD-SHAPED FILLERS FOR CIGARETTE FILTERS OR THE LIKE [75] Inventor: Heinz Greve, Hamburg, Germany [73] Assignee: Hauni-Werke Karber & Co. KG,

Hamburg, Germany 22 Filed: July 16,1971

211 Appl. No.: 163,376

[30] Foreign Application Priority Data Primary ExaminerLouis K. Rimrodt Attorney-Michael S. Striker [5 7] ABSTRACT A tow which consists of filamentary filter material and is being converted into a continuous rod-like filler prior to wrapping to form a wrapped filter rod is being withdrawn from a bale wherein the filaments of the tow are likely to become interlaced or entangled with attendant short-lasting changes in tensional stresses upon the tow. Such short-lasting changes in the tensional stresses are clamped upstream of the point where the tow is engaged by a pair of advancing rollers to insure that the tension in those increments of the tow which advance beyond such rollers is substantially constant. The damping action can be brought about by aroll which rests in a loop of the tow between the advancing rollers and the bale and which is biased by a spring which compensates for the weight of the roll. The latter rises in response to increasing tension inthe loop to reduce the length of such loop and descends in response to decreasing tension of the loop to thereby lengthen the loop at a speed which is preferably proportional to the extent of changes in the length of the loop.

10 Claims, 1 Drawing Figure PAIENTED $744 108 l/n e/rfor:

H E I N 2 GR E VE HUORNEV METHOD AND APPARATUS FOR MAKING ROD-SHAPED F ILLERS FOR CIGARETTE FILTERS OR THE LIKE CROSS-REFERENCE TO RELATED APPLICATIONS The apparatus of the present invention constitutes an improvement over and a further development of filter rod making apparatus which are disclosed in my copending application Ser. No. 130,287 filed Apr. l, 1971 for Method and Apparatus for Regulating the Operation of Filter Rod Making Machines and in my copending application Ser. No. 131,167 filed Apr. 5, 1971 for Method and Machine for the Production of Filter Rod Sections or the Like.

- BACKGROUND OF THE INVENTION The present invention relates to a method and apparatus for the production of continuous rod-like fillers which can be wrapped to form filter rods for use in the production of filter rod sections ready to be assembled with wrapped tobacco rod sections to form filter-tipped cigarettes, cigarillos, cigars or like smokers products. More particularly, the invention relates to improvements in a method and apparatus for manipulating a tow of fibrous filter material which is being withdrawn from a bale to be converted into a rod-shaped filler.

It is well known to produce rod-shaped fillers for wrapped filter rods by withdrawing a continuous tow consisting of filamentary filter material from a bale and by spraying successive increments of the tow with a plasticizing agent which is thereupon caused to harden or set while the thus treated tow is converted into a rod.

, The hardened plasticizer serves as a bonding agent between the filaments of the resulting filler rod and insures that the filaments remain in optimum positions with reference to each other during severing of the wrapped filler rod to yield filter rod sections of unit length or multiple unit length.

As a rule, the tow is stretched prior to contact with a spray of plasticizing liquid. Such stretching or elongation of the tow is desirable because its filaments are stored in the bale in a crimped condition. An elongation of successive increments of the tow insures that each increment which is contacted by the plasticizing liquid contains substantially the same number of filaments which are of substantially identical length. Therefore, successive increments of the resulting filler rod exhibit a desirable uniform resistance to the passage of smoke in the axial direction of the filler in a filter rod section. Such uniform resistance to flow of smoke in the axial direction of the filler in a filter for cigarettes or the like is an important factor because the smoker is annoyed if a first filter cigarette offers a relatively low resistance and the next-following cigarette offers a relatively high resistance to the flow of smoke through the filter. The resistance of the filler rod to the passage of smoke is a function of the density of fibrous filter material which, in turn, is a function of proper stretching or elongation of successive increments of the tow prior to contact with the plasticizing agent. Such uniform elongation of the tow is difficult to achieve in presently known filter rod making apparatus, mainly because of the fact that the filaments in contacting portions of the tow in a compacted bale are likely to become entangled and to thereby affect the rate at which the tow is being withdrawn from the bale. For example,

when a tow portion whose filaments are entangled with the adjacent portion or portions of the tow which forms the bale is about to be withdrawn, the interlocking filaments offer a relatively high resistance to withdrawal with attendant rise in tensional stress upon the tow between the advancing rollers and the bale. As soon as the just discussed portion of the tow is forcibly disengaged from the adjacent portion or portions, the tensional stress upon the tow between the bale and the advancing rollers decreases abruptly with attendant changes in the density of increments which advance beyond the advancing rollers and into the range of the device which applies to the filaments an atomized plasticizing agent. As mentioned above, the presently known apparatus for the production of filter rods for cigarettes or the like are unable to satisfactorily cope with such abrupt fluctuations in tensional stresses upon a tow of fibrous filter material.

SUMMARY OF THE INVENTION An object of the invention is to provide a novel and improved method of compensating for changes in tensional stresses upon the filaments of a tow which is being withdrawn from a bale for conversion into the rod-shaped filler of a wrapped filter rod.

Another object of the invention is to provide a method of at least reducing the undesirable effects of abrupt changes in tensional stresses upon successive portions of a tow of fibrous filter material which is being withdrawn from a bale wherein the filaments of adjoining portions of the stored and condensed tow are likely to interlock and to cause abrupt changes in tensional stresses during withdrawal of the tow from the bale.

A further object of the invention is to provide an apparatus for converting a tow of filamentary filter material into a rod-shaped filler for filter rods with simple, compact, reliable, rugged and inexpensive means for counteracting the undesirable effects of abrupt changes in tensional stresses upon the tow during withdrawal from the bale.

An additional object of the invention is to provide a novel and improved damping device which can compensate for abrupt changes in tensional stresses upon a tow of filamentary filter material and which can be incorporated into existing apparatus for the production of filter rods whose parts are to be used in filter cigarettes or like smokers products.

The method of the present invention is employed for the production of a continuous rod-shaped filler which includes a continuous tow consisting of filamentary filter material. The method comprises the steps of withdrawing the tow from a bale with attendant recurring short-lasting changes in tensional stresses upon the tow, and damping the changes in tensional stresses upon the tow.

The withdrawing step preferably comprises subjecting successive increments of the tow to the action of a pulling force at a point which is located at a predetermined distance from the bale whereby the changes in tensional stresses develop in that portion of the tow which extends between the bale and such point. The damping step comprises changing the length of such portion of the tow. The damping step may further comprise changing the length of such portion of the tow at a rate of speed which is proportional to the extent of such changes in length.

The novel features which are considered as characteristic of the invention are set forth in particular in the appended claims. The improved apparatus itself, however, both as to its construction and its mode of operation, together with additional features and advantages thereof, will be best understood upon perusal of the following detailed description of certain specific embodiments with reference to the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING The single FIGURE is a fragmentary schematic side elevational view of an apparatus for the production of rod-like fillers for cigarette filters which embodies the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The drawing illustrates a portion of a filter rod making apparatus similar to that known as KDF and produced by Hauni-Werke Korber & Co. K.G., of Hamburg-Bergedorf, Western Germany. The illustrated apparatus includes a first main section 1 which is shown in greater detail and a second main section 2 which is shown only in part. The construction of the second main section 2 is preferably identical with that of the apparatus shown in my aforementioned copending applications Ser. Nos. 130,287 and 131,167. The second section 2 includes a funnel-shaped condensing horn 23 which serves to convert a properly treated tow 4 of filamentary filter material into a rod-like filler which is ready for wrapping into a web of paper, cork or the like.

The heretofore employed components of the first main section 1 include a container 6a for a bale 6 of filamentary filter material which is stored in the form of the aforementioned tow 4. This tow is continuously withdrawn from the bale 6 by a pair of advancing rollers 3 one of which is driven by a variable-speed transmission 16 which receives motion from the main prime mover here shown as an electric motor 14. The latter also drives the moving parts of the second main section 2. On their way to the nip of the advancing rollers 3, successive increments of the tow 4 advance past two opening or spreading nozzles 7 and 8 which serve to loosen the filamentary material of the tow 4 prior to treatment of the tow by a bonding medium in the form of a liquid plasticizer 13 stored in a source or tank 18. The advancing rollers 3 are followed by a first pair of tensioning rolls 9 and thereupon by a second pair of tensioning rolls 11. The aforementioned tank 18 forms part of a treating unit 12 which is installed between the tensioning rolls 9 and 11. One of the tensioning rolls 9 and one of the tensioning rolls 11 is preferably provided with circumferential grooves (not specifically shown) and the complementary tensioning rolls 9 and 11 are preferably provided with smooth peripheral surfaces. The material which is adjacent to such smooth peripheral surfaces is preferably rubber or elastomeric synthetic plastic material.

The motor 14 drives the lower tensioning roll 9 by means of a first endless chain or belt 14a, and the lower tensioning roll 9 drives the input member of the transmission 16 by means of a second endless belt or chain 14b. A third endless belt or chain 140 drives the lower tensioning roll 11. and a fourth endless belt 14d transmits motion to the movable components of the section 2. The RPM of the driven advancing roller 3 is less than the RPM of the driven tensioning roll 9 so that the filaments of the tow 4 undergo a certain elongation during transport between the advancing rollers 3 and the tensioning rolls 9. The ratio of the transmission 16 can be adjusted by an electric servom'otor 17.

The treating unit 12 further comprises a rollershaped withdrawing member 21 which dips into the supply of liquid plasticizer 13 in the tank 18 and is driven by a separate electric motor 19. A rotary brushshaped applicator 22 is driven by the lower tensioning roll 9 through the intermediary of an endless belt or chain Me and serves to atomize the film of liquid plasticizer which is being withdrawn by the peripheral surface of the withdrawing member 21 and to spray the thus atomized plasticizer across the path of the tow 4 between the tensioning rolls 9 and 11. The tensioning rolls 9 and 11 flatten the tow 4 whose filaments are loosened by the nozzles 7 and 8 so that the particles of liquid plasticizer which are sprayed by the applicator 22 are distributed with considerable uniformity to all or nearly all filaments of that portion of the tow which is located above the member 21 and applicator 22. The thus treated increments of the tow 4 are thereupon caused to pass through the horn 23 and to be converted into a rod-like filler which is wrapped and thereupon severed to yield filter rod sections of desired length. The manner of wrapping the rod-like filler forms no part of the present invention.

In accordance with a feature of the present invention, the first main section 1 of the filter rod forming apparatus further comprises a damping unit 28 which is installed at a station 26 located between the nozzle 8 and the advancing rollers 3, i.e., upstream of the point where the tow 4 is being pulled and downstream of the bale 6. The purpose of the damping unit 28 is to form in the tow 4 a loop 27 and to damp abrupt changes in tensional stresses upon the tow by changing the length of the loop 27. Such abrupt changes in tensional stresses upon the tow 4 arise because the bale 6 is compacted and because the filaments of the tow 4 are twisted and curled so that they are interlaced in the bale. The tension in the tow 4 increases when a group of interlaced filaments in a portion or section of the tow 4 which is about to be withdrawn from the bale 6 is strongly interlaced with the filaments of the adjacent tow portions. When the tow portion to be withdrawn is extracted from the bale 6, the tension in the top between the bale and the advancing rollers 3 decreases abruptly, often all the way to zero, and thereupon increases again when the slack is taken up by the advancing rollers. The purpose of the damping unit 28 is to damp such abrupt changes in the tension of the tow portion between the advancing rollers 3 and the bale 6. The damping unit comprises a mobile loop former here shown as including a dancer roll 31 which rests on the tow 4 in the bottom part of the loop 27 and is rotatably mounted on one arm of a support here shown as a twoarmed lever 32 which is pivotably supported by a horizontal pin 32a on a bearing bracket 33. The other arm of the lever 32 is biased in a counterclockwise direction, as viewed in the drawing, by a helical spring 34 which compensates for the weight of the dancer roll 31. A deflecting roller 29 is mounted upstream of the dancer roll 31 to deflect the tow 4 as it advances beyond the nozzle 8. The loop 27 begins at the roller 29 and ends at the advancing rollers 3.

The operation:

It is assumed that the advancing rollers 3 rotate at a constant speed (the upper advancing roller 3 is biased against the tow 4 in the nip between the rollers 3 and is thus rotated at the exact speed of the driven roller 3 but in the opposite direction; the same holds true for the upper tensioning rolls 9 and 11) whereby the rollers 3 draw the tow 4 from the bale 6 so that successive increments of the tow advance along the nozzles 7, 8, along the deflecting roller 29 of the damping unit 28, along the dancer roll 31, between the advancing rollers 3 and tensioning rolls 9, through the treating unit 12, between the tensioning rolls 11 and toward the horn 23. If the filaments of the tow portion which is about to be withdrawn from the bale 6 are interlaced with the adjacent filaments, the resistance of such portion of the tow to withdrawal by the advancing rollers 3 increases with attendant rise in tensional stressing of the tow between the container 6a and the advancing rollers 3. The dancer roll 31 is caused to rise against the action of gravity by pivoting about the axis of the pin 32a for the lever 32 in a counterclockwise direction, as viewed in the drawing, and toward the lower advancing roller 3. This reduces the tensional stress upon the tow portion between the container 6a and the lower roller 3 because the length of the loop 27 is allowed to decrease. Due to the illustrated positioning of the lever 32, its pivot 32a, and dancer roll 31 with reference to the deflecting roller 29 and advancing rollers 3, the resistance to movement of the dancer roll 31 about the axis of the pivot pin 32a in response to tensioning of the tow 4 between the container 6a and the rollers 3 increases with attendant rise in the tensional stress upon the tow. When the tow portion which is about to be withdrawn from the bale 6 is suddenly released due to disentanglement of its filaments from the adjoining filaments, the tensional stressing of the tow between the rollers 3 and the container 6a decreases rapidly and the dancer roll 31 descends by moving about the pivot pin 32a in a clockwise direction, as viewed in the drawing, to

- thereby increase the tensional stress upon the two between the advancing rollers 3 and the bale 6. This will be readily understood since, when the lowermost portion of the tow 4 is abruptly freed and is being with drawn from the container 6a, the loop 27 is unable to support the dancer roll 31 from below so that the latter descends under the action of gravity and lengthens the loop 27 with attendant increasein the tensional stress. Thus, the drop in tensional stressong of the tow downstream of the dancer roll 31 is not as pronounced as in the region upstream of the dancer roll. The latters descent under the action of gravity is damped by the spring 34 to thus prevent an abrupt increase in the tensional stress upon the tow 4 between the advancing rollers 3 and the container 6a. As a rule, the dancer roll 31 returns to the illustrated normal or neutral position without any appreciable oscillation; it normally comes to rest in the illustrated position at the termination of its clockwise orbital movement about the axis of the pivot pin 32a.

It was found that the changes in length of the loop 27 contribute very effectively to elimination of abrupt and substantial changes in tensional stressing of these increments of the tow 4 which enter the space between the tensioning rolls 9 and 11. Since the length of the loop 27 cannot be changed within a very wide range without unduly increasing the dimensions of the filter rod forming apparatus, the roll 31 is preferably mounted with reference to the advancing rollers 3 and with reference to the deflecting roller 29 in the abovedescribed manner, namely, so as to insure that the changes in length of the tow portion between the container 6a and the advancing rollers 3 are carried out at a speed which is proportional to the extent of such changes. The roll 31 stores energy during lifting by the loop 27, Le, in response to increased tensioning of the tow 4 between the advancing rollers 3 and the bale 6, and dissipates energy during movement back toward the normal position which is shown in the drawing.

An important advantage of the damping unit 28 is that it insures substantially uniform tensioning of that portion of the tow 4 which extends between the tensioning rolls 9 and 11. This guarantees uniform distribution of atomized liquid plasticizer 13 to all or nearly all filaments of the expanded and loosened tow before such filaments reach the tensioning rolls 11. Uniform distribution of liquid plasticizer in each increment of the tow 4 is important in order to insure that each portion of the rod-like filler which is formed in the second main section 2 of the illustrated apparatus exhibits the same resistance to the passage of smoke in the axial direction of the filler.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features which fairly constitute essential characteristics of the generic and specific aspects of my contribution to the art and, therefore, such adaptions should and are intended to be comprehended within the meaning and range of equivalence of the claims.

What is claimed as new and desired to be protected by Letters Patent is set forth in the appended claims:

1. In a method of producing a continuous rod-like filler of filamentary filter material wherein the filler includes a continuous tow of filaments, the steps of withdrawing said tow from a bale-wherein sections of the tow are stored with their filaments in crimped condition and interlaced with each other so that the withdrawal of said tow sections entails recurring shortlasting changes in tensional stresses upon the tow as a result of separation of interlaced filaments of said tow sections from each other; and damping said changes in tensional stresses upon the tow.

2. In a method as defined in claim 1, wherein said withdrawing step comprises subjecting successive increments of the tow to a pulling force at a point located at a predetermined distance from said bale whereby said changes in tensional stresses develop in that portion of the tow which extends between said bale and said point, said damping step comprising changing the length of said portion of said tow.

3. In a method as defined in claim 2, wherein said damping step further comprises changing the length of said portion of said tow at a speed which is proportional to the extent of such change in length.

4. In an apparatus for producing a continuous rodlike filler of filamentary filter material wherein the filler includes a continuous tow of filaments and is being withdrawn from a bale containing tow sections whose filaments are crimped and interlaced with each other so that the withdrawal of said tow sections entails recurring short-lasting changes in tensional stresses upon the tow as a result of separation of interlaced filaments of said tow sections from each other, a combination comprising advancing means spaced apart from said bale and arranged to advance the tow lengthwise whereby said changes in tensional stresses develop in that portion of the tow which extends between said bale and said advancing means; and damping means engaging said portion of the tow and arranged to damp said changes in tensional stresses in said portion of the tow.

5. A combination as defined in claim 4, wherein said damping means comprises a mobile loop former which loops said portion of said tow upstream of said advancing means.

6. A combination as defined in claim 5, wherein said mobile loop former comprises a spring-biased dancer roll engaging said portion of said tow.

7.'A combination as defined in claim 5, wherein said loop former comprises a support pivotable about a substantially horizontal axis and having first and second arms, a dancer roll engaging said portion of said tow and mounted on one of said arms, and resilient means engaging the other of said arms to balance the weight of said dancer roll.

8. A combination as defined in claim 4, wherein said advancing means comprises a pair of cooperating advancing rollers and variable-speed drive means for at least one of said rollers.

9. A combination as defined in claim 4, wherein said damping means includes a dancer roll engaging the tow upstream of said advancing means and positioned with reference to said advancing means in such a way that its resistance to the lifting action of the tensioned tow increases while the dancer roll approaches said advancing means.

10. A combination asdefined in claim 9, wherein said damping means further comprises a deflecting member for the tow, said dancer roll being located between said advancing means and said deflecting member. 

1. In a method of producing a continuous rod-like filler of filamentary filter material wherein the filler includes a continuous tow of filaments, the steps of withdrawing said tow from a bale wherein sections of the tow are stored with their filaments in crimped condition and interlaced with each other so that the withdrawal of said tow sections entails recurring shortlasting changes in tensional stresses upon the tow as a result of separation of interlaced filaments of said tow sections from each other; and damping said changes in tensional stresses upon the tow.
 2. In a method as defined in claim 1, wherein said withdrawing step comprises subjecting successive increments of the tow to a pulling force at a point located at a predetermined distance from said bale whereby said changes in tensional stresses develop in that portion of the tow which extends between said bale and said point, said damping step comprising changing the length of said portion of said tow.
 3. In a method as defined in claim 2, wherein said damping step further comprises changing the length of said portion of said tow at a speed which is proportional to the extent of such change in length.
 4. In an apparatus for producing a continuous rod-like filler of filamentary filter material wherein the filler includes a continuous tow of filaments and is being withdrawn from a bale containing tow sections whose filaments are crimped and interlaced with each other so that the withdrawal of said tow sections entails recurring short-lasting changes in tensional stresses upon the tow as a result of separation of interlaced filaments of said tow sections from each other, a combination comprising advancing means spaced apart from said bale and arranged to advance the tow lengthwise whereby said changes in tensional stresses develop in that portion of the tow which extends between said bale and said advancing means; and damping means engaging said portion of the tow and arranged to damp said changes in tensional stresses in said portion of the tow.
 5. A combination as defined in claim 4, wherein said damping means comprises a mobile loop former which loops said portion of said tow upstream of said advancing means.
 6. A combination as defined in claim 5, wherein said mobile loop former comprises a spring-biased dancer roll engaging said portion of said tow.
 7. A combination as defined in claim 5, wherein said loop former comprises a support pivotable about a substantially horizontal axis and having first and second arms, a dancer roll engaging said portion of said tow and mounted on one of said arms, and resilient means engaging the other of said arms to balance the weight of said dancer roll.
 8. A combination as defined in claim 4, wherein said advancing means comprises a pair of cooperating advancing rollers and variable-speed drive means for at least one of said rollers.
 9. A combination as defined in claim 4, wherein said damping means includes a dancer roll engaging the tow upstream of said advancing means and positioned with reference to said advancing means in such a way that its resistance to the lifting action of the tensioned tow increases while the dancer roll approacheS said advancing means.
 10. A combination as defined in claim 9, wherein said damping means further comprises a deflecting member for the tow, said dancer roll being located between said advancing means and said deflecting member. 